The new Dreamliners are up to 20 percent more fuel efficient than similar models. New engines from General Electric (NYSE:GE) are credited for the most substantial improvements in fuel efficiency. Boeing says that the engines represent a “two-generation jump in technology for the middle of the market. GE came under fire when some problems with the engines were reported and a flight was preemptively cancelled, but issues have reportedly been resolved.

Half of the Dreamliner, including the fuselage and wings, is made from composite materials, making it lighter than other models.

Reports from the first flight have been generally positive — passengers seem to love the plane.Gregory Karp at the Chicago Tribunereports glowing reviews from passengers, praising everything from how smooth the ride was to details like how lavatory doors revolve in, instead of out.

“If you want to be the world’s leading airline, you need to have the world’s leading airplane, and we have that today in the new Boeing 787 Dreamliner,” said United CEO Jeff Smisek.

United is among 58 Dreamliner customers worldwide. Boeing has orders for at least 835 units valued at over $180 billion.

Perhaps coincidentally, shares of United are trading as much as 1.8 percent higher in the early afternoon. The introduction of the Dreamliner into the fleets of major airlines is more than just interesting, it’s expected to save billions in fuel costs. United could be well on its way to a competitive advantage with 50 Dreamliners in the air.